1. Field of the Invention
The invention relates generally to vehicle bodies, such as truck and trailer bodies, shipping containers and the like, and more particularly to insulated vehicle bodies made of composite panels and to modularly constructed vehicle bodies.
2.Reference to Prior Art
Intermodal shipping containers are widely used in the freight transport industry where different modes of transport (e.g. sea, rail and roadway) are used to ship the containers from one point to another. To permit connection to both container transports, such as ships, rail cars, and trailer beds or chassis and to other intermodal containers, it is well known to provide each container with lock receiving fittings at standard locations.
To optimize performance, it is desirable that containers (or other vehicle bodies) be light weight and have maximum interior space to accommodate a maximum payload without exceeding weight restrictions. If insulated or refrigerated, it is also desirable that containers be thermally efficient, while at the same time possessing the structural properties needed for rigorous service.
Containers constructed essentially of metal components are well known. An example of such a container is provided in U.S. Pat. No. 4,819,280 issued Apr. 11, 1989 to Weiner. While metal constructions, possesses good structural properties, they are also heavy and increases the tare of the container, thereby reducing payload capacity.
Insulated containers using metal components are also well known. For example, in one known insulated (or refrigerated) container wall construction, foamed insulating material is provided between aluminum posts separating outer metallic skins (e.g., aluminum sheets) from metal or plywood inner skins. This wall construction results in high thermal losses and increased weight resulting from the use of metallic components. Additionally, the metallic components are subject, in some instances, to corrosion and fatigue, especially with respect to fasteners used in the construction.
To decrease thermal losses somewhat, it is known to add wooden or plastic spacers between the metallic posts and the outer skins. Examples of the use of such spacers are provided in U.S. Pat. No. 3,432,979 issued Aug. 25, 1966 to Heimann, and U.S. Pat. No. 3,229,441 issued Jan. 18, 1966 to Heffner. However, improvements in thermal performance are accompanied by increased wall thicknesses that reduce interior cargo space.
Insulated containers having laminated walls are also known. One such wall is produced using a method known as the "Graf technique". That method involves laminating sheet material over an insulating core material. Laminated or sandwich wall constructions are susceptible to delamination which, once begun, can propagate along the entire wall. Delamination structurally compromises the wall and permits entry of contaminants, such as water, into the interior of the wall. This reduces the effectiveness of the insulating material and increases the overall weight of the container. Additionally, if a portion of the wall is significantly damaged satisfactory repair is difficult.
A trailer body constructed using plastic materials and intended to be lightweight and thermally efficient is illustrated in U.S. Pat. No. 3,003,810 issued Oct. 10, 1961 to Kloote et al. That trailer body has a monocoque construction and includes walls assembled of a plurality of panel members. Each panel member includes a central core of foamed polystyrene which is the primary load bearing member, plywood sublaminae bonded to the opposite faces of the core, and fiber reinforced polyester skins covering the plywood sublaminae. The panel members are interconnected using splines to form a sandwich wall structure having a substantially uninterrupted core. This construction suffers from delamination problems mentioned above with respect to the Graf technique and is further not structurally suited to handle loads encountered by intermodal containers.
Another example of an insulated trailer body construction utilizing non-metallic components is provided in U.S. Pat. No. 2,962,323 issued Nov. 29, 1960 to McBride. The McBride patent illustrates a trailer body including walls assembled of individual panels supported on a metallic frame. Each panel includes a "styrofoam" core covered by woven fiberglass cloth impregnated with polyester resin, and is joined to adjacent panels with an adhesive material and metal bolts. Disadvantages of this wall construction include, the thermal "leaks" and "shorts" presented by holes for the fasteners and the fasteners themselves.